In general, tillers have a number of tines which are mounted on a single horizontal shaft and rotated in order to provide a substantially slicing or scything action in which the tines cut through the soil in order to cultivate same. The vast majority of garden tillers, and in particular garden tillers intended for home use, are directly supported (and only supported) by their tines. Usually these tines are provided in a number of tine sets or tine groups.
Each set typically takes the form of a stamped metal “disk” with 4 to 6 tine “teeth.” Typically each disc can only cut in one direction of rotation. Furthermore, each disc is typically attached to a hollow hub which slides over a horizontal shaft. The shaft in turn supports and rotates the tines. Such tine sets are typically keyed to the shaft by means of a dowel or pin which extends through a radial hole in the driving shaft and hollow hub of the tine set. In order to have such a radial hole or other through hole drilled through the shaft, the shaft needs to have a substantial diameter. A large diameter shaft is able to withstand the weakening effect of the through hole for the dowel or pin.
Alternatively, the tine disc is “keyed” to the shaft by means of a “D”-shaped aperture in the disc which mates with a machined flat on one side of the shaft. Again a large diameter shaft is required because the presence of the machined flat weakens the shaft. In addition, the need to machine such flats and shape such apertures adds to the cost and complexity of manufacture.
Each pair of tine sets is positioned so that each set lies to a corresponding side of the longitudinal centre line through the tiller. Such tillers typically include a detachable pair of spaced apart wheels which are detached prior to cultivation, and reattached afterwards for the purpose of wheeling the tiller from one cultivating location to another which is close by. For more distant transportation, such garden tillers are provided with one or two handles which extend transverse to the longitudinal axis of the tiller. Such handle(s) are for the purpose of permitting the tiller to be lifted into the trunk or boot of an automobile. Some prior art tillers intended for commercial use are provided with a single, fixed height, ground engaging wheel which is used for transport. Another prior art tiller has a pair of spaced apart ground engaging wheels which support the tiller both during transport and during cultivation as will be described hereafter in more detail. Another prior art tiller having a single wheel is known. However, the arrangement of the tiller is such that the entire weight of the tiller located between the wheel and the handles must be supported by the operator during cultivation. This is extremely tiring. If the tiller is not supported in this way, the tiller can accelerate away from the operator. In order to arrest this acceleration, it is necessary for the operator to lift the handles of the tiller.
In an effort to ensure that adequate tilling of the soil is achieved during cultivation, most tillers have been designed so that the weight of the engine acts to drive the tines downwardly into the soil. As a consequence, the operator in seeking to adjust the depth of penetration of the tines into the soil is required to counteract the gravitational force generated by the mass of the engine. In order to achieve this, tillers are always provided with two handles and it is generally necessary for the operator to walk behind the tiller with bent arms. The operator has to adjust the height of the tines by bending the arms whilst at the same time partially supporting the weight of the engine. This is very tiring.
Without exception, tillers have a housing which extends below the level of the shaft carrying the rotatable tines, and which houses a gear box or drive chain arrangement (or similar) which transmits the rotary motion of the engine to the shaft. This housing is normally centrally located on the shaft and there are equal numbers of tines on the left and right of the housing. As a consequence, the soil immediately below the housing tends to be less well cultivated than the soil to either side of the housing. Under some difficult soil conditions (e.g. hard clods, small hummocks, and the like) this inhomogeneous tilling action can be disadvantageous.
Searches after the priority date have disclosed various prior art arrangements.
FR 2316, 852 MALIND FINANZ-ANSTALT and CH 520, 461 KUNSTER both disclose a single wheeled mower with a hollow tubular shaft which extends in front of the mower and which terminates in a pair of reciprocating sets of horizontal mower blades. A drive mechanism for the mower blades extends through the hollow shaft, and one or more handles are located to the rear of the wheel. The centre of gravity is forward of the wheel so that the mower blades engage the grass if the operator does not hold the handles.
U.S. 2005/004537 STARK uses a pair of wheels to support the engine of a sweeper/cultivator in which the centre of gravity is forward of the wheels so that the sweeper drum engages the surface to be swept.
JP 08-224001 YANMAR AGRICULTURAL EQUIPMENT Co LTD discloses a tiller with a resistance rod for tilling and a trailing wheel for transport. The wheel and rod are rotatably mounted about a horizontal axis and one or the other is rotated downwardly to come into action whilst the other is rotated upwardly and out of the way. The centre of gravity of the tiller is forward of the trailing wheel.
SU 1128847 AS BELO TECH CYBERN (MISW) discloses a plough which is reciprocally mounted for fore and aft motion controlled by a hydraulic cylinder. The plough does not rotate but instead slides through the earth.
DE 2,555,525 FROLICH discloses a tiller with a spoked hub to set the cultivating depth. The spokes step over stones in order to not leave a rut in the tilled earth. The tiller engine is above the tines so the centre of gravity is forward of the spoked hub.
DE 4,210,816 BAUER discloses a tiller with a leading ground engaging wheel forward of the cultivating tines. The motor is positioned above the tines and a resistance rod is located at the rear.
FR 2,586,888 DENIS discloses a tiller with a leading ground engaging wheel and a tine axle located behind the front wheel. The tine axle extends to one side only of the longitudinal axle of the device.
U.S. Pat. Nos. 5,826,667 and 6,116,350 NOTARAS each disclose a lawn edger with a leading cutter blade assembly for edging grass growing over a concrete curb or pavement, a ground engaging wheel behind and the power unit to the rear of the wheel. The wheel is intended to roll along a sidewalk or footpath adjacent the edge of the lawn edge to be cut.
U.S. Pat. No. 6,516,598 NOTARAS discloses a vegetative trimmer similar to U.S. Pat. No. 5,826,667 but with a cutting head able to be rotated to cut either vertically or horizontally.
The genesis of the present invention is a desire to provide a different ergonomic arrangement for tillers and so to some extent lessen the abovementioned fatigue and permit a more homogenous tilling action to be achieved under difficult soil conditions.